84 EECORD OF CURRENT RESEARCHES RELATING TO 



hollow, thick-walled tubes. From the abundant nerve-supply of the 

 parapodia, and from the fact that some of the nerve-fibres can be 

 distinctly traced to the organs in question, Graber is inclined to 

 think that they are sensory in function. 



4. Bep-oductive Organs. — The author has confirmed his former 

 statement, that T^jiMoscolex (Acicularia) is dioecious and not, as Uljanin 

 states, hermaj)hrodite. 



Worm Fauna of Madeira.* — Dr. Paul Langerhans contributes a 

 paper of eighty pages, illustrated by three plates, on the Syllidce of 

 Madeira. He gives a revision of the family, dividing it into three 

 tribes — Syllidece, Exogonece, and Autolytece. He also describes one 

 new genus — 0])isthodonta — and splits up the genus Syllis into four 

 subgenera as follows : — 



1. Sjillis with single sette in all segments (Haplosyllis). 



2. Syllis with similar compound setae in all segments (TyposylUs). 



3. Syllis with similar compound setae in all segments, but having 

 besides on many, or on nearly all the segments, single setae of 

 strikingly different form : these may be either comj)ound or simple 

 (^Ehlersia). 



4. Syllis with compound seta3 in the hinder segments, simple 

 in the middle, and sometimes also in the anterior segments (Syllis 

 proper). 



The various species of these subgenera, as well as those of the 

 other genera of the family, are fully described. 



In his concluding remarks, the author gives some interesting facts 

 as to the disposition of the setfe of Syllis gracilis. In this species 

 some (16-21) of the anterior segments have the usual compound setae. 

 Then follow a few (2—4) with mixed armature — that is, with both the 

 compound setae and the simple setae characteristic of the species ; then 

 a very variable number (26-77) with simjjle setae only; then a few 

 (2-11) with both kinds; and, finally, the remaining 3-13 with only 

 the compound kind. 



It will be seen that the greatest variation is in the middle segments 

 bearing the simple setae, and, according to the characteristic mode of 

 formation of the segments in these worms, these segments are the 

 youngest. In correspondence with this, it was found that young 

 specimens of Syllis gracilis had no segments with simple setae, but 

 only those with compound and mixed setae : these, then, corresponded 

 exactly to the subgenus Ehlersia. In others, again, still younger, 

 both simple and mixed setae were absent, only compound ones present, 

 this stage corresponding to the subgenus Typosyllis. Similarly 

 young individuals of Ehlersia rosea were found, having only the 

 compound setfe characteristic of the whole genus Syllis (Syllis 

 Forsteri). It would thus seem that the three subgenera, Typosyllis, 

 Ehlersia, and Syllis proper, represent three stages in the evolution of 

 the whole genus Syllis — Typosyllis being the oldest, Syllis proper the 

 youngest form. According to this view, the simple seta is a fui'ther 

 development of the compound one, not vice versa, and Langerhans 



* 'Zeitsch. wiss. Zool.,' xxxii. (1879) p. 513. 



